Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
The use of mobile computing devices such as laptops, notebook computers, personal digital assistants (PDAs) and cellular telephones to access the Internet is becoming increasingly popular. These mobile computing devices enable users to move from one location to another, or “roam,” while continuing to maintain connectivity to the Internet. To facilitate fast and secure mobile computing with such devices, an extensive infrastructure has been put in place that includes multiple wireless communication networks deployed over extensive and typically overlapping geographical areas and which typically conform to one or more industry-wide mobile IP standards for routing information to a user.
Mobile IP (Internet protocol) allows location-independent routing of IP datagrams on the Internet to a roaming mobile computing device, or “mobile node.” Each mobile node is identified by its home address independent of its current physical location. When away from its home network, a mobile node is associated with a care-of address identifying its current location while the home address is associated with the local endpoint of an IP tunnel to the home agent of the mobile node. Using mobile IP, a mobile node may change the point-of-attachment to the Internet, i.e., the local endpoint of the IP tunnel to the home agent, without changing the home IP address, thereby allowing the mobile node to maintain transport and higher-layer connections while roaming. Thus, mobile IP provides an efficient, scalable mechanism for roaming within the Internet, so that the user of a mobile node has access to the Internet regardless of where a user is located and whether the user is stationary or moving.